The present invention relates to tires, and, in particular, to a pneumatic tire which is mounted on a safety rim and which is inflated by a plurality of individual balls.
For off-road vehicles, it is desirable to have low tire pressure in order to have better traction and higher speeds. However, if the tire pressure is reduced enough to obtain the desired traction, there is a severe risk of rim and tube damage when the tire hits a bump or other irregularity. Failure of the rim or a flat tire will prevent the competitor from finishing the event. Flat tires are a common cause of poor competitive performance by an otherwise capable competitor. In recent years, the more financially able competitors have adopted the use of foam tire inserts to replace conventional “inner” tubes. While these inserts solve the problem of flat tire failure, they can decompose and cause underinflated tires. They also create poorer traction due to the apparent high inflation pressure when compared to conventional inner tube/tire combinations at the normal inflation pressures. They are also expensive and have a very limited useful life. Therefore, while foam tire inserts perform a useful function, they do not fully solve the problems encountered in the art.
Individual balls have been used to support a tire in the past. Our research found patents between the years 1890 and 1921 that taught the use of individual  balls to support a tire. For example, U.S. Pat. No. 442,393 “Richwine” shows a tire A, which surrounds balls E and which is laced onto studs C on the rim. Most of those prior art balls were solid or thick-walled, relying on the stiffness of the material of the ball to provide support to the tire. Later, around 1920, tires were developed using inner tubes, and the use of internal balls inside a tire was abandoned. These newer types of tires generally required the tire to be installed onto a two-piece rim in a deflated state. Once the tire was installed on the rim, it was inflated. While this type of tire provided a softer, more comfortable ride than was possible with the earlier tires, the two-piece rim was dangerous, and people occasionally were injured when the rim came apart under pressure. Around the early 1940s, the safety rim came into use. This was a one-piece rim with internal recesses that received the edges of the tire. The edges of the tire seated against the rim along those internal recesses. The use of these safety rims is now the norm, with the tire being installed onto the safety rim and then inflated, either with or without the use of an inner tube.